Question

What is the two sided Confidence Interval for X?

Given

      X̄ = 199.3 cm

      s = 16.3 cm

      n = 18 (Unitless)

      Confidence = 97.5 %

      IT IS IMPORTANT TO REPORT CONFIDENCE INTERVALS CORRECTLY:

      Report them as "(L < μ < U) with __ % Confidence",

       with appropriate numbers substituted for L, U and Confidence.

      Omit L or U if the Confidence Interval does not have a Lower or Upper Limit.

Question(s)

1. If you repeated this problem many times--with a new sample collected from X each time--what percentage of the Confidence Intervals thus estimated would you expect to include the true mean?

2. What is the Significance of the Confidence Interval? Note: answer is decimal, NOT percent.

3. What probability will be used to calculate the Critical Value (i.e., is placed in tail)? Again: answer is decimal, NOT percent.

4. Calculate the Degrees of Freedom.

5. Calculate the Critical Value used to determine the Confidence Limit(s). Use a Student T Table.

6. Calculate the Lower Limit of the Confidence Interval.

7. Calculate the Upper Limit of the Confidence Interval.

Answer 1